There is presently a great demand for economically and easily installed roofing systems suitable for rooms added to existing residential construction. Among the qualities desired in a roofing system in such an application are that it be economically, quickly, and easily installed; that it require a minimum of maintenance and that it provide an effective barrier to weather. Further, increases in energy costs have accentuated the need for the roofing system to provide an effective thermal barrier. In fact, increased heating and air conditioning costs have made the presence of insulation between the roof and the ceiling a necessity, even in moderate climates, for economical year-round enjoyment.
One roofing system that particularly provides for convenient and economical installation of an insulated roof is disclosed in U.S. Pat. No. 4,155,206. However, the roofing system disclosed there shares a deficiency with other insulated roofing systems prior to the present invention in that it fails to address two problems.
A significant improvement over prior roofing systems is herein provided by an economical and rapidly installing insulated roofing system that eases alignment requirements of roof and ceiling installation and which provides for differences in thermal expansion between the roof and the ceiling due to differences in temperature, material and configuration.